Calutron receivers



5, 1955 s. P. FRANKEL CALUTRON RECEIVERS 2 Sheets-Sheet 1 Filed Aug. 29, 1945 INVENTOR. JTANLE Y A FeA/wra Nov. 15, 1955 s. P. FRANKEL CALUTRON RECEIVERS 2 Sheets-Sheet 2 Filed Aug. 29, 1945 INVENTOR. fim/vLfy/Q PEA/W451.

United States Patent CALUTRON RECEIVERS Stanley P. Frankel, Los Angeles, Calif as'signor to the United States of America as represented by the United States Atomic Energy Commission Application August 29, 1945, Serial N04 613,357

Claims. (Cl. 250-413) The general subject of the invention involves the separation, based on difference in mass, of minute particles, such as atoms, and especially the separation of isotopes of an element, or the separation of a portion of an element enriched with respect to a particular isotope on a scale yielding commercially useful quantities of the collected material.

The type of means or mechanism to which the invention relates is known as a calutron, and correspondingly the method or process is known as a calutron method or process. In its presently preferred form, a calutron comprises an evacuated chamber mounted in a substantially homogeneous magnetic field and containing apparatus for ionizing a polyisotope to be treated, apparatus for projecting a beam of ionized particles of the polyisotope along paths determined by the masses of the respective ions, and a target apparatus for deionizing the particles of the beam and for retaining at least one selected isotope component in a separated region from which it can be recovered.

In general, the calutron comprises an evacuated tank placed between the poles of an electromagnet so that the evacuated space within the tank is pervaded with a magnetic field of high flux density. Within the tank there is provided a source or source unit which includes means for supplying the polyisotope as a vapor or gas to an ionizing region, ionizing apparatus for producing positively ionized particles from the vapor, and an accelerating device maintained at a high negative electrical potential with respect to the ionizing apparatus for withdrawing the positive ions and imparting to each of them a predetermined energy in the form of substantially uniform velocities along paths generally normal to the direction of the magnetic field toward a beam defining slit. in the accelerating device disposed generally parallel to the direction of the magnetic field.

The accelerated ions move transversely to the magnetic field and are constrained to travel along arcuate paths having radii that vary with the masses of the particle. By virtue of the accelerating slit construction the paths for the ions of a given mass diverge from a median path to an extent determined by the geometry of the ionizing and. accelerating devices. This divergence of the paths of travel of the ions of a given mass continues through the first 90 of arcuate travel and then the paths converge during the next 90 and cross each other in a region of focus approximately 180 from the source unit.

The geometrical considerations involved result in the arcuate orbital paths of the ions of a particular given mass becoming tangent to a circle twice the diameter of the orbit circle diameter. The locus of the points of tangency for a given angular divergence of the ions at the source unit. will extend to either side of the 180 focus position through a similar angular extent along the larger circle. Thus the ions of one mass, for example, will have their paths tangent to a circle of a given 2,724,058 Patented Nov. 15, 1955 diameter, while the ions of a smaller mass will have their paths tangent to a circle of slightly smaller diameter, this amount depending solely upon the mass difference of the respective ion constituents of the beam.

The present invention relates particularly to the portion of a calutron provided in the target region and which will be referred to as a receiver," the receiver being positioned in the general region of the l focus of the beam.

It is a general object of the invention to provide improved apparatus and methods for receiving ions in a calutron.

Another object of the invention is to provide an ion receiver unit which takes advantage of the geometrical property involved in aca'lutron whereby ions of a given mass will have their orbits tangent to a common circle in the region of focus.

Another object of the invention is to provide baffle means for intercepting ions of a particular mass while allowing passage of ions of another mass.

Another object of the invention is to provide a receiver unit incorporating a vane system located in the region of focus of the ion beam to intercept ions of a particular mass and a collector positioned posteriorly with respect to the vane system to receive ions which pass the vane system.

Other objects and advantages of the invention will become apparent from the following description of a preterred form of the invention as disclosed in the accompanying drawings, in which:

Figure 1 is a schematic view illustrating in horizontal cross section a calutron embodying the instant invention;

Fig. 2 is a schematic view illustrating the relation of the vane system to ions of a mass that pass the system;

Fig. 3 is a schematic view similar to Fig. 2 showing the relation of the vane system to ions of a mass which are intercepted thereby;

Fig. 4 is a schematic view of a modified form of the invention showing a bafile positioned to intercept ions of a given mass; and

Fig. 5 is a schematic view similar to Fig. 4 showing the relation of the baffle to ions of a lesser mass.

The calutron disclosed herein is of the general type of that disclosed in the application for United States Letters Patent of Ernest 0. Lawrence, Serial Number 557,784, filed October 9, 1944 for Methods of and Apparatus for Separating Materials, now Patent No. 2,709,222 to which reference is made for a complete disclosure of all of the operative parts of a calutron. Only such calutron parts as are necessary to an understanding of the instant invention will be described herein.

The calutron includes a tank 10 which is mounted be tween the pole faces 11 of the calutron magnet, one of the pole faces being seen in Fig. 1. In the present instance, the pole faces arevertically spaced apart and the lower pole face is' illustrated. As a result of the arrangement of the pole faces, the direction of the magnetic' field is perpendicular to the plane of the drawing and in the present instance the polarity of the faces is so selected that the field is directed inwardly with respect to the drawing. The' interior of the tank 10 is connected by a conduit 12 to suitable pumping means 13 for maintaining a desiredlow pressure within the tank. Within the tank a source unit 14' is provided including a source block 15 mounted by suitable insulators 16 upon a-wall of the tank 10, and including means for producing ionized particles forwithdrawal through an exit opening 17 by meansof an accelerator electrode 18. As illustrated, the source block 15 ismaintained at a high positive potential, while the accelerating electrodes 18 are maintained at a morenegative potential, in the present instance at ground, so that the positive ions formed within the source block 15are withdrawn to form an ion beam. For further detailed description of a suitable source unit reference is made to the above-identified Lawrence application.

5 As previously explained, the operation of the accelerata ing device and the source unit in general causes the projection of the ions through divergent paths extending through a given angle to either side of a median ion masses 234 and 235, so that the sample collected in the pocket 22 will represent uranium enriched with respect 7 to the isotopes 234 and 235.

path to form anion beam as illustrated schematically at 19. In the present instance it has been assumed for illustrative purposes that theangular divergence of the ion paths to either side of the median ion path is 10. It will be understood that .for each ion mass there will be a similar distribution at the point of emergence of the ions from between the accelerator electrodes and that subsequently the ions of each mass will follow similar orbital paths of a given radius; for different isotopes of the charge material will vary in accordance with the mass difference of the respective isotopic ions. For example, if normal uranium is employed as the charge material, the U+ ion beam is made up of components of U U and U As previously explained, the ions of each mass travel through paths which become tangent to a circle of twice the diameter of the orbit path of the ion with the points i of tangency extending to either side of the 180 position i this purpose the receiver unit includes a series of vanes 21 located in the region of focus of the ions at the 180 position and ahead of a collector 22. The collector 22 is supported by an insulator tube 23 which extends through the wall of the tank 10 and in turn is suitably supported by a second insulator tube 24. The vanes 21 are disposed in a direction parallel to the direction of the magnetic field and with their left-most or inner edges 26 lying on a circle of a diameter to intercept the U ions while allowing U and U ions to pass by and into the collector 22. Fig. 3 is illustrative of the paths of U ions to show their interception by the vanes 21.

Figs. 4 and 5 illustrate schematically a modified form of the invention wherein the ion intercepting means is in the form of an arcuate bafiie 27 which is located with its inner surface along the circle containing the edges 26 of the vanes 21, Fig. 4 illustrating the interception of U ions'by the bafiie, while Fig. 5 illustrates the passing of U ions by the baffle.

The operation of the ion receiving means illustrated herein may be briefly summarized as follows. As previously explained, the operation of the source unit provides an ion beam which diverges from a virtual focus in the source region for an angular extent to either side of a median path; and the paths of the various ions, by virtue of the influence of the magnetic field, are arcuate, and because of the presence of ions of different mass the ion beam tends to become separated into its various isotopic components in the region of focus located 180 from the source region, so that in this region of focus it is possible to achieve at least a partial separation of the isotopic components and produce material enriched with respect to a particular isotope.

By virtue of the geometrical considerations present, it is possible by appropriate arrangement of beam intercepting means in the form of a baffle or a series of vanes to intercept ions of greater mass whose paths become tangent to a circle of twice the diameter of the circular path followed by each ion. Consequently, by positioning the edges of the vanes closest to the source, or the surface of the arcuate baffle facing the source, on a circle representing the circle of tangency for ions lying between The radii of the paths While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein and it is intended to cover in the appended claims all such modifications as fall within the tmespirit and scope of the invention.

What is claimed is:.

1, In a calutron having means for establishing an ion beam and means for effecting a momentum separation of ions of different mass in said beam, an arcuate plate located in a region of focusing of said beam and positioned outside the focusing region of ions of lesser mass to intercept ions of heavier mass while passing said ions of lesser mass, and a collector for said ions of lesser mass.

2. In a calutron having means for establishing an ion beam and means for effecting a momentum separation of ions of different mass in said beam, a series of beam intercepting vanes having similar edges disposed in areaate array in the region of fousing of said beam and positioned outside the focusing region of ions of lighter mass to intercept ions of heavier mass, and a collector for ions of lighter mass which pass said vanes.

3. In a calutron having means for establishing an ion beam which diverges from a source region to either side of a median ion path and means for effecting a momentum separation of ions of different mass in said beam whereby ions of different rnasses arrive at a region of focus wherein ions of each mass have their paths tangent to a common circle, a series of beam intercepting vanes with their beam defining edges located in circular array on a circle outside the focusing region of ions of lighter mass between the respective circles of tangency of ions of adjacent masses to intercept ions of heavier mass, each vane being disposed parallel to the magnetic field of the calutron, said series of vanes extending to either side of a region of sharpest focus of the beam for an angular extent substantially corresponding to the angular divergence of the beam at the source region, and a collector, for receiving ions of lighter mass passed by said vanes.

4. In a calutron having means for establishing an ion a tum separation of ions of different mass, in said beam whereby ions of different masses arrive at a region of focus wherein ions of each mass have their paths tangent to a common circle, beam intercepting means disposed on a circle outside the focusing regions of ions of lighter mass between the respective circles of tangency of ions of adjacent masses to intercept ions of heavier mass, said beam intercepting means being disposed parallel to the magnetic field of the calutron and extending to either side of a region of sharpest focus of the beam for an angular extent substantially corresponding to the angular divergence of the beam at the source region, and a collector for receiving ions of lighter mass passed by said beam intercepting means.

5. In a calutron having means for establishing an ion beam which diverges from a source region to either side of a median ion path and means for effecting a momenturn separation of ions of different mass in said beam whereby ions of different masses arrive at a region of focus wherein ions of each mass have their paths tangent to a common circle, an arcuate baffle located parallel to and outside of said region of focus of ions of lighter mass with its center of curvature in the source region References Cited in the file of this patent adjacent the point at which said ion beam begins its UNITED STATES PATENTS divergence, said baffie having a surface disposed to intercept ions of a heavier mass while passing ions of 21 2,331,189 Hlpple 1943 lighter mass, and a collector for receiving ions passed 5 by said baffle. 

1. IN A CALUTRON HAVING MEANS FOR ESTABLISHING AN ION BEAM AND MEANS FOR EFFECTING A MOMENTUM SEPARATION OF IONS OF DIFFERENT MASS IN SAID BEAM, AN ARCUATE PLATE LOCATED IN A REGION OF FOCUSING OF SAID BEAM AND POSITIONED OUTSIDE THE FOCUSING REGION OF IONS OF LESSER MASS TO INTERCEPT IONS OF HEAVIER MASS WHILE PASSING SAID IONS OF LESSER MASS, AND A COLLECTOR FOR SAID IONS OF LESSER MASS. 